Suspension apparatus for auto-focus lens device and a method for fabricating the same

ABSTRACT

A suspension apparatus comprises a lens holder, a suspension spring and a supporting base. The supporting base is formed with an opening for accommodating the lens holder. The lens holder is for positioning a lens unit. The suspension spring is manufactured by stamping process to form a long strip with a plurality of suspension springs. The strip is then guided into a mold, and plastic injection molding process is performed in that mold so as to produce the lens holder and supporting base affixed respectively to either end of the suspension spring in one piece. After that, excess material of the strip is cut off. The suspension apparatus as above described is suitable for mass production. In addition, because of the high precision of mold, the inaccuracy of assembly and fabrication is minimized. The volume of the whole apparatus and the cost of production are also vastly decreased.

Related Applications

This application is a Division of application U.S. Ser. No. 11/197,432,entitled “A SUSPENSION APPARATUS FOR AUTO-FOCUS LENS DEVICE AND A METHODFOR FABRICATING THE SAME” and filed on Aug. 5, 2005 now U.S Pat. No.7,158,316.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates to a suspension apparatus for auto-focuslens device and a method for fabricating the same, more particularly anapparatus used in camera which provides the functions of suspension andsupport by forming a lens holder and a supporting base respectively ateither end of a suspension spring in one piece by means of plasticinjection molding.

2. Description of the Prior Art

A standard camera 1 comprises a lens set 11, a sensor 12 and a focusingmechanism (not shown in the figure). The lens set 11 forms an image onsensor 12 by refracting the light rays from an object (as shown in FIG.1). If the distance between lens set 11 and sensor 12 (back focallength, BFL) is fixed, the lens can only show clearly objects at aspecific distance (e.g. the hyperfocal distance of 2-3 meters away). Forthe camera to shoot objects at a close distance, the distance betweenlens set 11 and sensor 12 must be adjusted using a focusing and zoomingmechanism.

The focusing and zooming mechanism 2 used in conventional camera (asshown in FIG. 2) typically includes an expensive precision drive element21 (e.g. stepping motor, ultrasonic motor, and piezoelectric actuator)to supply the power needed to drive the lens holder 22 that carries thelens set 11 and a large number of driving elements. Such design has thedeficiencies of complicated mechanical configuration, time-consumingassembly, bulkiness and high cost. Most seriously, it consumes a largeamount of power. As technology advances, camera makers have been gearingtheir efforts towards developing high picture quality and small-sizedproducts for easy carriage. Other electronic device makers also focus onintegrating more functions in one device by, for example, combining thefunctions of photographing and mobile communication of handset, thefunctions of photographing and personal digital assistant (PDA), or thefunctions of photographing and notebook computer to give the device morepowerful video functions. Based on the design of a common power supplyhaving the same capacity as that for a device with single function, howto reduce the size and the cost of product, how to lower powerconsumption to effectively improve the standby time and run time of theintegrated product become the focus of research for electronic productmanufacturers.

In conventional focusing and zooming lens structure, an elastic elementis often used to provide the functions of cushion, positioning andrepositioning. A conventional lens unit 3 as shown in FIG. 3 comprises alens mount 31 and a lens frame 32. The lens mount 31 has lens 311 at thetop, a hollow space 312 in the middle, and an electromagnetic coil set33 wound around its periphery at the bottom. The lens frame 32 isarranged in the space 312 of lens mount 31 and able to slide up and downthe space 312. The lens frame 32 has two protruding members (not shownin figure) and the shape of space 312 complements that of lens frame 32so that lens frame 32 will not turn in space 312 when sliding. The lensframe 32 is made of magnetically conductive metal material so that themagnetic force generated after the electromagnetic coil set 33 arecharged can attract the lens frame 32 to displace downward. The lensframe 32 is disposed with a lens 321 therein. The upper part and lowerpart of space 312 in lens mount 31 has respectively an upper stop member313 and a lower stop member 314 with lens frame 32 situated therebetweenand a spring 34 disposed between the lens frame 32 and lower stop member314. By such structural design, the lens frame 32 in the lens unit 3 canbe pushed against the upper stop member 313 by the thrust from thespring 34. At the time of focus adjustment, electric current is passedthrough electromagnetic coil set 33 to generate magnetic force that canattract the metallic lens frame 32 to displace downward and achieve theobjective of focus adjustment.

In the conventional lens unit structure just described, the spring 34used is bulky, hence taking considerable space. On the other hand, incoordination with the use of spring 34, an upper stop member 313 and alower stop member 314 must be disposed in the upper and lower sectionsof space 312 in lens mount 31, rendering the whole structure morecomplicated. Conventional lens unit assembles the lens mount 31, lensframe 32 and spring 34 one by one after they are separately fabricated.The whole assembly process is not only tedious and time consuming, theunavoidable inaccuracy in assembly also adds to the burden of qualitycontrol operation.

SUMMARY OF INVENTION

The primary object of the present invention is to provide a suspensionapparatus for auto-focus lens device and a method for fabricating thesame, characterized in which a lens holder and a supporting base areformed respectively at either end of a suspension spring in one piece bymeans of plastic injection molding, which offers the advantages ofsimplified assembly process and cost reduction.

Another object of the present invention is to provide a suspensionapparatus for auto-focus lens device and a method for fabricating thesame, which can effectively reduce assembly inaccuracy because of thehigh precision furnished by plastic moulds.

A further object of the present invention is to provide a suspensionapparatus for auto-focus lens device and a method for fabricating thesame, whereby one-piece molding is employed to allow the suspensionspring in the apparatus to provide the functions of cushioning andrepositioning for the two-way movements of lens holder and to greatlycut down structures required to connect various components so as toeffectively reduce the volume of the whole apparatus.

Yet another object of the present invention is to provide a suspensionapparatus for auto-focus lens device and a method for fabricating thesame, wherein a flat-surface, circuitous and extending connecting memberis designed in a suspension spring to provide a cushioning elasticityand greatly reduce the space needed.

To attain the aforesaid objects, in a preferred embodiment of theinvention, the suspension apparatus for auto-focus lens device and amethod for fabricating the same comprises a lens holder, a suspensionspring and a supporting base. The supporting base is formed with anopening for accommodating a lens unit. The suspension spring ismanufactured by stamping process to form a long strip with a pluralityof suspension springs. The strip is then guided into a mold, and plasticinjection molding process is performed in that mold, so as to producethe lens holder and supporting base affixed respectively to either endof the suspension spring in one piece. After that, excess material ofthe strip is cut off. The suspension apparatus as above described issuitable for mass production. In addition, because of the high precisionof mold, the inaccuracy of assembly and fabrication is minimized. Thevolume of the whole apparatus and the cost of production are also vastlydecreased.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of the present invention will be more readily understoodfrom a detailed description of the preferred embodiments taken inconjunction with the following figures.

FIG. 1 is a diagram showing the focusing and zooming principle ofconventional lens.

FIG. 2 is an exploded view of conventional focus and zoom lens.

FIG. 3 is a sectional view of a conventional focus and zoom lens.

FIG. 4 is a schematic diagram of the suspension spring in the suspensionapparatus for auto-focus lens device according to the invention.

FIG. 5 is an external view of a plurality of lens holder and supportingbase formed on suspension spring in the suspension apparatus forauto-focus lens device according to the invention.

FIG. 6 is an external view of the suspension apparatus for auto-focuslens device in one piece after the removal of excess material.

FIG. 7 is the flow process diagram showing the method for fabricatingthe suspension apparatus for auto-focus lens device according to theinvention.

FIG. 8 is an external view of an embodiment of the present inventionmounted in a focusing device.

DETAILED DESCRIPTION

FIGS. 4, 5 and 6 show a preferred embodiment of the suspension apparatusfor auto-focus lens device and a method for fabricating the sameaccording to the present invention. FIG. 4 is a schematic diagram of asuspension spring in the suspension apparatus for auto-focus lensdevice; FIG. 5 is an external view of the long strip in the suspensionapparatus for auto-focus lens device formed in the injection moldingprocess; FIG. 6 is an external view of the suspension apparatus forauto-focus lens device with suspension spring and supporting baseattached thereto in one piece and excess material cut off.

As shown in FIG. 4 and FIG. 5, the suspension apparatus for auto-focuslens device in this embodiment comprises a lens holder 4, a suspensionspring 5 and a supporting base 6. The supporting base 6 is formed withan opening 61 (please refer to FIG. 6) for accommodating the lens holder4. The lens holder 4 is for positioning a lens unit (not shown in thefigure). The suspension spring 5 is a flat plate made of metallicmaterial by stamping process and further arranged with a basepositioning end 51 and a lens holder positioning end 52 (as shown inFIG. 4) with at least one connecting member 53 formed therebetween. Theconnecting member 53 is a thin-strip structure with multiple bends (e.g.in S-shape) to allow limited bend and swing between base positioning end51 and lens holder positioning end 52 so as to furnish cushioningelasticity and repositioning elasticity. The base positioning end 51 andthe lens holder positioning end 52 on suspension spring 5 arerespectively disposed with at least one through-hole 54 for positioning.

Based on the structure described above, the supporting base 6 and lensholder 4 can be formed simultaneously as two independent elements bymeans by injection molding, and in the same injection molding process,become attached to suspension spring 5 utilizing the through-holes 54disposed on the base positioning end 51 and lens holder positioning end52 of suspension spring 5 (as shown in FIG. 5). With the elasticityfurnished by the connecting member 53 of suspension spring 5, the lensholder 4 can be suspended and maintained a position in the opening 61configured in supporting base 6. By the aforesaid structure, the presentinvention not only saves the time of fabricating and assemblingindividual elements, the structure of individual elements which at timesbecomes complicated in consideration of assembly needs is alsosimplified. The cost of production is also vastly decreased.

In comparison with the spring 34 used in conventional structure, theflat suspension spring 5 used in the invention takes less space, thushelping to reduce the volume of the whole apparatus and making itsuitable for application in other portable electronic products (e.g.mobile phone, PDA or notebook computer). The suspension spring 5 alsoprovides two-way suspension support. On the other hand, the connectingmember 53 with a plurality of bends in the suspension spring 5 not onlyincreases the supporting force for lens holder 4 in a limited space, iteffectively adds to the stroke length of lens holder to allow broaderapplications.

FIG. 7 is a flow process diagram illustrating the method for fabricatingthe suspension apparatus for auto-focus lens device, which is a simplerfabrication process in light of the structure described above (as shownin FIG. 7). This method features the steps of first manufacturing a longstrip by stamping process (step 71), and then guiding the strip ofsuspension spring into a precision plastic mold (step 72) to producesimultaneously a plurality of supporting bases and a lens holderattached to either end of the suspension spring in one piece by plasticinjection molding as shown in FIG. 5 (step 73). The excess material isthen removed (step 74) to form a unitary member as shown in FIG. 6.Using the supporting force furnished by suspension spring 5, lens holder4 can be suspended in the opening 61 configured on supporting base 6 andengage in limited vertical displacement relative to the supporting base6 under external force. When lens holder is not under external driving,it is kept at a fixed position under the reposition force of suspensionspring 5. By the fabrication method just described, the suspensionapparatus of the present invention is suitable for mass production. Inaddition, because of the high precision provided by plastic mold, theassembly inaccuracy is minimized and the fabrication process simplified.The volume of the whole apparatus and the cost of production are alsosignificantly decreased.

FIG. 8 is an external view of an embodiment of the present inventionmounted in a focusing device 8, in which the lens holder 4 is furtherarranged with a lens barrel 41 thereon and a cover 81 is snapped to thesupporting base 6. The cover 81 and lens barrel 41 are not adjoined toeach other. The bottom of the supporting base 6 is connected with abottom plate 82 and a sensor 83 (CMOS/CCD sensor). The periphery of lensholder 4 is disposed with a plurality of coil winding members forwinding a plurality of drive coils 84. On the supporting base 6corresponding to the drive coils 84, there disposes a permanent magnetset 62 comprised of two magnets with opposing poles. The drive coils 84includes at least a first coils 841 and a second coils 842 disposedrespectively on the opposite sides of lens holder 4. The permanentmagnet set 62 includes at least a first magnet 621 and a second magnet622 stacked together and corresponding to the first coils 841 (or secondcoils 842) arranged on lens holder 4. The first coils 621 and secondcoils 622 are stacked together and wound in opposite directions thattheir poles facing the lens barrel 41 oppose each other. As such, theupper portion and lower portion of the permanent magnet set 62 facingthe lens barrel 41 have opposing poles. At the same time, the locationof first magnet 621 corresponds exactly to the horizontally extendedcoils from the upper half of first coils 841 (or second coils 842),while the second magnet 622 corresponds to the horizontally extendedcoils from the lower half of first coils 841 (or second coils 842). Whena direct current is applied to first coils 841 (or second coils 842),the current directions of the horizontally extended coils at its upperhalf and lower half are opposite to each other as shown in FIG. 8,which, coupled with the first magnet 621 and the second magnet 622stacked together with opposing poles, generates same direction drivingforce (e.g. upward or downward).

When lens barrel 41 is about to shift position, a predetermined currentis passed through the first coils 42 and the second coils 43 disposed onlens holder 4, causing the two coils 42, 43 to generate magnetic linesin specific directions. The resulting magnetic action between firstmagnet 621 and second magnet 622 furnishes the force to push the lensholder 4 forward (upward) or backward (downward) along the axis of lensbarrel 41. As such, the lens holder 4 holding the lens barrel 41 movestowards a predetermined direction to change the distance between lensbarrel 41 and sensor 83 so as to achieve the purpose of focusing andzooming.

The snap-fit mechanism between cover 81 and supporting base 6 comprisesa plurality of beveled protruding members 63 formed on the supportingbase 6 coupled with a plurality of engaging holes 811 on cover 81 at thelocations relative to the protruding members 63 (as shown in FIG. 8),such that cover 81 is secured to supporting base 6 through theengagement between engaging holes 811 and protruding members 63.

Through the structural design just described, the present invention ofsuspension apparatus for auto-focus lens device is able to reduce itsoverall volume, which represents excellent progress and contribution tominiaturization and enables it to be used in more products (e.g.notebook computer with built-in monitor or other portable electronicproducts) to provide better focusing and zooming function. The use ofplastic injection molding to form supporting base 6, lens holder 4 andsuspension spring 5 in one piece also greatly simplifies themanufacturing and assembly process that not only helps reduce productioncost, but also addresses the problem of assembly inaccuracy.

The description above presents only a preferred embodiment of thepresent invention. In fact, the present invention can similarly offerthe advantages of increasing the density of magnetic lines and theefficiency of magnetic force by arranging the permanent magnetic set ona movable lens holder and disposing the first coils and second coils onthe supporting base.

1. A suspension apparatus for auto-focus lens device, comprising: a lensholder for positioning a lens unit; a supporting base formed with anopening for accommodate the lens holder; and at least a suspensionspring comprising a base positioning end, a lens holder positioning end,and at least a connecting member situated therebetween; said connectingmember providing the reposition elasticity between base positioning endand lens holder positioning end; wherein the lens holder is adjoined tothe lens holder position end and the supporting base is adjoined to thebase positioning end, wherein at least a drive coils are disposed on theperiphery of lens holder, and at least a permanent magnet set isarranged on supporting base at the location corresponding to said drivecoils, wherein said permanent magnet set includes at least a firstmagnet and a second magnet stacked together with opposing poles so thatthe poles of first magnet and the second magnet facing the lens barrelare opposite to each other; as such, the upper half and the lower halfof said permanent magnet set facing the lens barrel have opposing poles,wherein when direct current is applied to said drive coils, the currentdirections of coils facing the first magnet and the second magnet areopposite to each other.
 2. The suspension apparatus for auto-focus lensdevice according to claim 1, wherein said suspension spring is made ofmetallic material.
 3. The suspension apparatus for auto-focus lensdevice according to claim 1, wherein said suspension spring ismanufactured into a long strip by stamping process.
 4. The suspensionapparatus for auto-focus lens device according to claim 1, wherein saidconnecting member has the shape of multiple bends.
 5. The suspensionapparatus for auto-focus lens device according to claim 1, wherein atleast one through-hole is disposed on the base positioning end ofsuspension spring for positioning.
 6. The suspension apparatus forauto-focus lens device according to claim 1, wherein by passing apredetermined current through the drive coils disposed on lens holder,the lens holder is able to carry out linear displacement in apredetermined direction.
 7. The suspension apparatus for auto-focus lensdevice according to claim 1, wherein the supporting base is furtherarranged with a cover engaged thereto.
 8. The suspension apparatus forauto-focus lens device according to claim 7, wherein a snap-fitmechanism funished between the cover and the supporting base comprises aplurality of beveled protruding members formed on supporting basecoupled with a plurality of engaging holes on the cover at the locationsrelative to the protruding members for engagement.
 9. The suspensionapparatus for auto-focus lens device according to claim 1, wherein saidsupporting base is further connected with a bottom plate and a sensorelement at its bottom.